(NBC NEWS) -- A resident of the gated community where Trayvon Martin was killed told a Florida court Friday he saw the unarmed teen punching George Zimmerman before the two had a fatal confrontation in February of 2012.
Jonathan Good was watching TV with his wife at the Retreat at Twin Lakes in Sanford, Fla., on Feb. 26, 2012, when a faint noise caught his attention, he told a Seminole County court Friday. When he heard more noise, he opened his sliding glass door, took a step outside, and spotted what "seemed like a tussle."
"I could really only see one person, and I think I described it as possibly being some type of dog attack, because there are a lot of dogs that walk in that back area," Good said.
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But as the figures rolled a little closer to Good on the rainy evening, he realized it was two people.
"And then at one point I yelled out, 'What's going on?' and 'Stop it,' I believe," Good told the jury, who is seated for Zimmerman's second-degree murder trial. Zimmerman has pleaded not guilty, claiming self-defense.
Good only saw the two fighting for what he described as "10 seconds, max" before running inside to call 911, but his eyewitness account of Martin's final moments could prove crucial for jurors and investigators in the case.
Good didn't recognize either men, and said one was straddling the other.
"I could tell the person on the bottom had a lighter skinned color," Good said. Zimmerman is of white and Hispanic descent, and Martin is black.
When one straddled the other, the person on the bottom was "face up," he said.
"I think at that time is when I thought it was serious," he said.
"OK. What made you think that?" prosecutor Bernie De La Rionda asked.
"'Cause it looked like there were strikes being thrown, or punches being thrown, but as I clarified, due to the lighting, it could have also been, you know, holding down. But there were arm movement[s] going downward," Good said.
"And the arm movements that you describe, would that have been from the person on top?" De La Rionda asked.
"Correct," responded Good.
Later, in cross-examination, defense attorney Mark O'Mara pressed Good for specifics of the confrontation.
"The person who you now know to be Trayvon Martin was on top, correct?" O'Mara asked.
"Correct," Good said.
"And he was the one who was raining blows down on the person on the bottom, George Zimmerman, right?"
"That's what it looked like," Good said.
Good added it was too dark to see many details, and said he was too far away. He also said he didn't see either person slam the other's head against concrete, something Zimmerman alleges Martin did and part of the reason he says he acted out of self-defense in shooting Martin.
But Good did say he later heard screams coming from one person, who he believed to be Zimmerman.
"If it was coming from on top it would have echoed off a wall instead of coming directly at me," he said.
He added he couldn't say for sure which person it was.
911 call played in court
Good's 911 call - which he placed when he heard the gun go off - was also played for the first time in court on Friday.
"Um, I'm pretty sure the guy's dead out here. Holy sh*t," he says to the 911 operator.
Martin's parents, Tracy Martin and Sybrina Fulton, sat quietly during Good's testimony. Fulton held "Our Daily Bread," a Christian monthly devotional, in her hand.
Parts of the cross-examination were decidedly antagonistic.
"Don't really want to be here, do you?" O'Mara opened his cross-examination by asking. "You were very reluctant to be involved in the case at all, correct?"
Good agreed that he was one of the only witnesses who had requested anonymity and had not wanted to partake in the trial.
O'Mara questioned Good about a martial arts phrase he had used with police officers in his initial statement to describe Martin and Zimmerman's fight.
"What you saw was the person on top in an MMA-style straddle position, correct? That was further described, was it not, as being 'ground and pound.' What is 'ground and pound' as you define it?" O'Mara asked.
"The person on top being able to punch the person on the bottom, but the person on the bottom also has a chance to get out or punch the person on top. It's back and forth," Good said.
O'Mara also demanded to know exactly what Good, who did not know either Zimmerman or Martin, saw that night, questioning him numerous times about his definition of being positioned in "vertical" and "horizontal" standings. Good, visibly annoyed at times, invited O'Mara to get down on his knees to demonstrate the positions he saw for the jurors, which the lawyer did.
Good is the next-door neighbor of Jenna Lauer, another resident at the Retreat at Twin Lakes gated community, who testified on Thursday. Lauer placed the 911 call that captured screams in the moments before Martin's death. On Thursday, she told the court that she heard "scuffling" that sounded like "sneakers on pavement and grass" before she called 911.
Editor's note: George Zimmerman has sued NBC Universal for defamation. The company strongly denies the allegation.